Modern gas turbine annular combustors are usually provided with a combustor which is of generally annular configuration. Usually a wall or bulkhead is provided at the upstream end of the combustor which is suitably apertured to receive a number of fuel burners. The fuel burners are equally spaced around the combustor and direct fuel into the combustor to support combustion therein. The combustor bulkhead is therefore usually close to the high temperature combustion process taking place within the combustor making it vulnerable to heat damage.
One way of protecting the bulkhead from the direct effects of the combustion process is to position heat shields on its vulnerable parts. Typically each heat shield is associated with a corresponding fuel burner and extends both radially towards the radially inner and outer extents of the bulkhead and circumferentially to abut adjacent heat shields. Each heat shield is spaced apart from the bulkhead so that a narrow space is defined between them. Cooling air is directed into this space in order to provide cooling of the heat shield an so maintain the heat shield and the bulkhead at acceptably low temperatures.
More recently cylinders comprising end flanges, commonly known as miniflares, have been used to direct a film of cooling air across the heatshield thus protecting it from hot combustion gases. However, although present miniflares provide a film of cooling air for the heat shield their own cooling is insufficient to prevent overheating, in particular towards its outer edge. Additionally the cooling film produced often ceases to be effective at the outer regions of the heatshield. It is an aim of the present invention, therefore, to provide an improved device for cooling a heatshield which attempts to alleviate the aforementioned problems.